1. Field of the Invention
The invention relates to a process and a device for marking molded items, tablets with monochrome or polychrome symbols, letters, numbers or break notches by applying the desired markings with the aid of a pulsed laser beam, the laser being arranged directly in a tablet-producing press.
The marking of solid forms of drugs is a necessity, in order to prevent the risk of confusion during manufacture and distribution, and to enable a rapid identification, for example in connection with cases of poisoning. It is for this reason, for example, that diverse recommendations or statutory requirements (GMP, among others) exist in many countries of the World. The manufacturers of solid drugs are dutybound to manufacture the latter in such a way that the risk of confusion is minimal as early as during the process of manufacture. Use of the above markings could further increase safety in this area. Monochrome or polychrome marking of molded items and tablets is possible by more than one process.
2. Description of the Related Art
A known process for the marking of tablets is the dying of the pressing mixture and/or stamping with stamping tools specially manufactured for the purpose. The disadvantages of this manufacturing process are a higher expenditure on development and more complicated formulae because of the dye distribution and/or stamping. Additional problems are occasioned by legal restrictions on the use of dyes, which are not always internationally uniform, and by the machine performance, which, due to the use of stamping tools, is not always as desired. In addition, depending on the stamping, the stamping tools are much more expensive than pressing tools in the absence of stamping. In addition, the formulae pressed with a stamping punch require a more intensive, ie. also a more expensive development, and the use of special auxiliary materials, because with the use of stamping punches, tablet formulae which can be pressed without a problem using normal, curved or plane punches can give rise to considerable difficulties depending on the nature of the stamping. Also in use are a number of processes for printed markings and, for example, an ink marking process, the so-called ink-jet printing system, is described in U.S. Pat. No. 4,548,825. In all these processes, the tablets are printed in a specially developed apparatus only once they have been manufactured, which means that the cost of the preparation is substantially increased. Moreover, during manufacture or intermediate storage, the risk of confusion mentioned above could well always be there. Another common process is the coating of tablets with films of different colors, the advantage being that all stampings, break grooves, etc. remain visible. The tablets to be film-coated must have a certain minimal curvature, which is important for the rolling movement in the coating apparatus. The disadvantage is that with curvature or additional stamping, the tablets become more difficult to press. In general, the film tablets require a considerably higher expenditure on raw material and development than does the tablet marking by dyeing the pressing mixture. It is also possible to sugar-coat tablets, but here, too, only biconvex molded items are capable of being sugar-coated well and the stampings and break grooves on the molded item or dragee core are covered over by the dragee coating, and so do not remain visible. Disadvantages are the long manufacturing period and the associated uneconomic nature of the manufacture of dragees.
The marking of tablets with the aid of lasers is fundamentally known (U.S. Pat. No. 3,657,510) and Defensive Publication T 903,014). However, both processes lack a system for the exact alignment of the tablets to be marked.
Even assuming that such apparatuses already exist for use in the marking of tablets, there remains the intermediate storage of the tablets to be marked after pressing and thus the risk of confusing tablets of similar appearance before or during the marking process.